Laptop Requirments and Linux Distro (Ubuntu/Kali Linux)

Hello guys so i have been lurking around here and i see a lot of interesting topics (as a newbie).So i want to ask you guys 2 questions.But first i have been stuyding python,html,css (To get that out of the way) 1)I am going to order a laptop and these are the specs Intel Core i3 5005U 2GHZ, 4GB ram, an intel hd graphic card,500 GB HDD and no os.I think that these specs are respectable as it costs 300 euro also i think i can install ubuntu on it as the laptop has no os but i see the same laptop in different shops and it says there FREE DOS, so i don't know the difference and if i can install ubuntu on there too.2)And my second question is why should i install kali linux and not ubuntu?I really don't understand the different i mean they are both linux distros and i use ubuntu in my class (that's why i chose it) and kali linux seams to me that is has a lot of tools,that's it, the only tools i am going to use are Wireshark because it is an amazing traffic analyser and aircrack ,all the other tools want to be made by me (I hope) and i know that the tools i am going to make wont be as effective as the others on kali linux but i will feel like a skiddie else.

Tell me what you think